The main focus of this thesis on spatial prepositions in contemporary standard colloquial Persian, but it may just as well be regarded as a study of the prepositional system since its scope extends well beyond the spatial domain. The analysis obtains observational and descriptive adequacy in scrupulously reflecting the linguistic knowledge of the Farsi speakers and provides a psychological view of the way the language user's mind produces and processes prepositions and prepositional phrases.

Generative grammar, particularly its Extended Standard Theory, provides the major theoretical framework upon which the present work is based. However, it also draws heavily on the findings of logical, geometric, cognitive, functional, and Space Grammar approaches to prepositions.

The thesis consists of three chapters. Chapter one deals with the syntax, morphology, and semantics of the ubiquitous ezafe. It shows that ezafe, whose host is always a [+N] constituent, is phonologically an enclitic morpheme, syntactically an associative marker, and semantically void of any features.

Chapter two explores the identity of prepositions. It questions the empirical and functional validity of the existing definitions and shows them to be inadequate and/or suffering from circularity. The bulk of such vagueness lies in the functional similarities between prepositions and conjunctions.

The contrasts between verbs and prepositions and between verbs and conjunctions demonstrates a closer functional affinity between the former than the latter two. A salient property is that a preposition is a category that may take an object, but is not a verb. Finally a criteria definition for prepositions is presented.

Chapter three is an extensive analysis of the semantics of prepositions. After discussing the issues of polysemy, homonymy, ambiguity, and non-specificity, it offers a survey of prepositions and justifies dividing them into two distinct groups: true prepositions (TPs) and pseudo-prepositions (SPs). The chapter examines the semantics of five simple spatial TPs and thirty six simple spatial SPs.

This study of prepositional semantics has three significant characteristics: it makes a distinction between the uses and senses of each polysemous preposition. It precludes the proliferation of senses by collapsing those which express a unified concept into more abstract superschemas. And it demonstrates that logical and geometric analyses cannot accurately describe spatial expressions unless they are accompanied by functional descriptions stemming from the speakers' knowledge of the world.